Dinosaurs were reptiles that evolved into the most varied kinds of any living creature. They ranged from tiny bird-like animals to monstrous beasts that were the largest animals ever to live on land. The dinosaurs survived for about 150 million years. They were not all the meat-eating killers familiar from films and books; neither were most of them gigantic creatures. In fact, most dinosaurs were peaceful, browsing animals about the size of modern farm livestock.
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